Conventionally, so-called back-incident type image pickup elements have been known. This type of image pickup element is provided with a light-incident surface at the back surface side of a semiconductor substrate, and picks up an optical image made incident from the light-incident surface by an image pickup unit being at the front surface side. As an image pickup device with such an image pickup element, there is provided, for example, a semiconductor energy detector described in Patent Document 1. This semiconductor energy detector is provided with a BT-CCD (Back-Thinned CCD) for which a part of the semiconductor substrate is thinned on the opposite side to the image pickup unit and which is capable of imaging various types of energy beams including ultraviolet rays, soft X-rays, and electron beams at a high sensitivity and a package electrically connected with the BT-CCD by wire bonding. The back-incident type image pickup element is used as, for example, a photodetecting section of a telescope for astronomical observation.
Patent Document 1: Japanese Published Unexamined Patent Application No. H06-196680